The planting of crops is usually performed by forming rows of raised soil and planting either seedlings or seeds at spaced intervals along the rows. Water, fertilizer, and/or other additives may be applied to the area of the seedlings and seeds and nature takes its course. This invention concerns seed planting.
In recent years, planting seeds through plastic mulch has become more popular. Plastic mulch planting is an agronomic practice in which a thin sheet of plastic known as plastic mulch is placed on the crop row before planting to cover the crop rows. A drip tape, a fumigant and other fluids may be placed under and trapped by the plastic mulch to treat the soil and plants. The trapping of the fluids under the plastic mulch reduces their loss due to evaporation. The plastic mulch also tends to retard the growth of weeds in the area of the plastic.
When planting starts, holes are formed at intervals in the plastic and the seeds are passed through the holes into the soil. The plastic mulch usually allows the plants to start earlier in the year in cooler temperatures since the beds usually are heated by sunlight and the plastic traps the heat at the surface of the soil. These and other factors tend to increase yields of plastic mulch planting from about 100% to 200% over conventional non-plastic mulch planting. In order to economize, the plastic mulch usually is used for more than one season's planting, so the planting of the crops needs to be as non-destructive of the plastic mulch as possible.
Generally, it is more labor intensive and, therefore, more expensive to plant through plastic mulch than when planting without the plastic mulch. The costs at the present time for plastic mulch planting can be from about $600 to $1,000 more per acre as compared to planting in bare ground.
There are some prior art mechanical planters that have been developed for forming spaced holes in the crop rows and dropping seeds in the holes. For example, mechanical planting of seeds is shown in U.S. Pat. Nos. 2,168,855, 2,778,291, 3,811,389, 4,023,511, 5,359,948, and 6,520,100. Other prior art planters that teach the planting of seeds through plastic mulch include the Renaldo-European Planter GVB520 available from Renaldo's Sales & Service in North Collins, N.Y., and U.S. Pat. No. 4,941,416. These devices form holes in the plastic mulch by burning with propane gas holes in the plastic and plunging an arm through the holes and blowing the seed with air into the holes in the soil. Water is applied to the holes. Accurate timing is required to avoid excessive burning of the plastic and to place the seeds through the burned holes. The device requires long timing chains and a supply of propane gas.
One of the problems with the prior art seed planters is the timing of the dispensing of the seeds from a container and moving the seeds through the holes in the plastic mulch and into the holes in the soil. Seed metering units have been developed and are available, such as the Singulaire 785 vacuum seeder available from Stanhay Webb Limited, Suffolk, England, that reliably dispense seeds, usually one or two at a time. The seeds are moved through a pipe to a planter such as a rotary drum that has radially protruding punch feet that have the ability to penetrate the plastic mulch and dig a hole in the soil. However, it is difficult to control the timing of the rotation of the rotary drum and its punch feet with respect to the seed dispenser. In some cases the seeds are not passed to the punch feet in a timed relationship that delivers the seed to the soil beneath the plastic mulch.
Typically the seed dispenser is located higher and outside of the perimeter of the rotary drum which is far from the punch feet of the feeder. The distance of travel of the seed from the seed dispenser to the punch feet is so long that any disruption of the ideal timing of delivery of the seed to the punch feet is likely to cause the seeds to be out of time with respect to the punch feet. Such disruptions in timing can be caused by vibrations and surges of the planter during its normal operation and the bouncing of the seeds within the seed tube that delivers the seeds to the punch feet.
The connection between the rotary drum and the seed dispenser usually is formed by a timing chain that extends from the axle sprocket of the rotary drum to a driven sprocket on the seed dispenser. This requires a long chain drive. Due to vibrations, surges of velocity, and other non-uniform forces encountered by the machine, the longer the chain drive the more likely it is to be difficult to maintain the seed dispenser in timed relationship with the punch feet of the rotary drum.
It is to the above-described problems that this invention is directed.